The Plantronics Blackwire C620-M is a dual earpiece over the head headset that is optimized for Microsoft Office Communicator 2007. It features both a noise and echo canceling mircrophone to enhance the clarity of one's conversation. It contains a QuickAdjust™ microphone boom which offers an adjustable boom angle, and microphone-to-mouth distance for optimal voice transmission. Protects hearing from loud sound spikes by limiting call volume at 118db with SoundGuard.